iOS 9.3.5 was the version that patched the infamous Pegasus spyware exploits. Jailbreaking with Phoenix re-exposes some of those vectors. Do not use this device for banking, sensitive work, or logging into iCloud with a primary Apple ID. The SSL and kernel patches are years out of date.
Every time your device crashes or you reboot, you must: Ios 9.3 5 Phoenix Jailbreak Tool